I Can't Kill Her
by NaughtyMustache
Summary: Marceline is ordered by her father to assassinate Princess Bubblegum, but somewhere along the line falls in love with her. Will she choose her kingdom or her feelings? Bubbline, lime in later chapters, a prompt from tumblr. Finished.
1. Chapter 1

Bubbline! My OTP. Time to add to the long strings of fanfics. This is about Marceline being ordered by her father to assasinate PB in order to take over the Land of Ooo, but ends up falling in love. Found the prompt on OTP Prompts tumblr

**Disclaimer: I do not own Adventure Time. All rights go to Pendelton Ward, you hilarious God you. **

**Warnings: fluff and lime, shaken not stirred. **

* * *

**I Can't Kill Her**

Marceline entered the Candy Kingdom with a satchel full of clothes and a mission. As she advanced up the annoying yellow road to the castle, the vampire scowled at the sugary subjects clumsily falling and naively laughing around her. It's a shame that they're going to be possibly enslaved after the nightosphere was finished with them. Her father Hunson Abadeer the Lord of Evil concocted a plan with her as the center.

It was quite simple in nature actually: Find the princess alone, kill her, and return to her father. Then the chaos of a fallen ruler will allow him to steal the royal thrown like candy from a baby.

Some strings were pulled to get her the position of the royal adviser, a job that gave her personal access to her royal highness without any overbearing guards. So she accepted the easy job to get back in her father's good graces considering she would soon be the queen of the Nightosphere.

_'Time to learn the family business,'_ she thought once she entered the edible castle. Greeted by a short peppermint man, she assumed the butler, Marceline was led to her chambers.

"This is where you'll be staying if all goes well. It's connected to her majesty's room right next door in case she needs your assistance." She observed the medium sized room oozing with pink and yellow decorations from the curtains to the king sized bed in the center that she poked to test the softness of.

Just like cotton candy as suspected.

The peppermint butler headed for the door, but was stopped by Marceline asking, "What do you mean 'if all goes well'?"

He coughed, embarrassed by the warning hint she caught. "You see, my princess Bubblegum isn't very... trusting of many. I've known her for her entire life and she still doesn't trust me. Let's just say royal advisers are often replaced. Any more questions?" She remained silent. "I'll be on my way then. Don't hesitate to ask me for anything." And what that said, he left and she was once again alone.

The gray haired teen floated to the white dresser and shoved the light load of clothes she brought in the drawers, then jumped in to the softness that was her bed, her body sinking like she was in a bean bag chair.

This mission would probably take a day to complete if Marceline took it seriously, but to her this was like a mini vacation.

Even if she's stuck in a fat girl's dream kingdom.

Still, a vacation was a vacation and she surely needed it. Lately her father has been showing a growing interest in her now that she was of age to take the throne, much more than he normally did which was saying a lot considering they had a bad relationship. She never has time for her music anymore which can totally stress her out.

A sound pulled her out of her thoughts, a soft, timid, melodious sound that came from the room next door. She had to hear Marceline floated towards the door, leaving it cracked open to peek at her mysterious target.

A slim figured appeared in her line of vision. Her skin a light pink, the oblivious princess wore a darker pink tanktop and fluffy pajama pants, gooey hair in a high ponytail. She tidied up the room while casually singing in a low, soothing voice:

_"Poor Lemonhope, I found you in the dark. You lived in the bathroom, now live in our hearts._

_Sweet Lemonhope, freed by hard sacrifice to live in the kingdom of sugar and spice.'_

She listened quietly to the lyrics, her eyes growing heavier and heavier... until she stumbled and fell when the princess said, "Who are you and why are you spying on me?" After picking herself up, she opened the door all the way and rubbed the back of her neck. How embarrassing to get caught like that.

"I'm Marceline, your new royal adviser. Didn't they tell you I was here?"

Answering a question with a question should help her avoid the reason they were even talking in the first place. Not that she could really focus on that already. The vampire couldn't stop looking at her heart-shaped face, plump cheeks, and thin lips. Somehow her ear caught the princess answering no. She smirked, leaning against the door frame, arms crossed over her chest.

"That must be awkward not knowing what's going on in your own kingdom," she commented.

The princess pouted adorably and mirrored her arms. "Still doesn't explain why you were watching me earlier." Shit. She remembered. "Uh, I heard you singing and got curious." A dark red blush somehow appeared on her face at the mention of her singing. She tucked her bangs behind her ear, looking down at the ground. "Oh. That. It's a song I made a while ago," she confessed, catching the music lover's attention.

"You write songs?"

"Sometimes. When I'm not busy. Why? Do you?"

"Yeah, I do. Maybe you could show me some of your songs one of these days."

"Hmm." The pink haired teen paused in thought. "Maybe."

Soon the room was quite, releasing a tense vibe as they stood awkwardly, not knowing what to say. It was the younger of the two that broke the silence. "Well, I should probably catch some zzz's. We'll talk more in the morning." Marceline nodded, relieved to be dismissed back to her room, and shut the door. A moment later she cursed herself.

That was the perfect opportunity and it was gone just like that.

Who knew when would be the next time she'd be alone with her. She sighed, changing into pj's and slipping under the cold comforter. _'It'd be a shame to rush this mission anyway,'_ she convinced herself. _'Good things come with time.' _Throwing something at the light switch, she descended into the darkness and her thoughts since she had no physical need to sleep. Unfortunately her thoughts rested on the pink princess she had just encountered.

This was going to be a long night.

* * *

Thank you for reading the first chapter of 'I Can't Kill Her'. This will probably be.. 3 chapters? Leave a review of how I'm doing so far!


	2. Chapter 2

**Disclaimer: I do not own Adventure Time.**

**Warnings: fluff, and lime in this chapter! **

* * *

At 2 in the morning, a loud creaking noise met Marceline's ear. Her deep brown eyes landed on the door connected to the princess's room that opened, leaking light in to the dark room. The pinkette peaked in, whispering," Marceline, are you awake?" The vampire sighed, nodding though she couldn't see.

"I'm up, princess peeping Tom," she teased, smirking at the rewarded blush. Round glasses sat on the bridge of her nose. _'Looks cute on her.'_ Woah. What the hell was Marceline thinking. Whatever it was, she pushed it to the back of her mind. Might as well have a bit of fun with her target before the deed was done. "And why might I ask are you in my room at such an _indecent_ hour? Your subjects surely don't approve of such disorderly conduct from _royalty_." The lights turned on, seemingly in retaliation, blinding the night dweller.

"I can't sleep and thought I could give you a tour of the castle if you were awake."

Confusion didn't leave her face as she reluctantly withdrew from the bed. "At 2 in the morning, princess?" Wow, she was a weird one.

"Yes. And don't call me that," she said when they left the room and wondered down the hall. "Then what should I call you? Your highness? Your majest? Oh great ruler of the Candy Kingdom?" Marceline heard her mumble something starting with a b.

"I can't hear you."

"I said Bonnibel."

_'Bonnibel,' _she thought over the name while looking at the quirky teen beside her. '_It works on her.' _She couldn't help, but ask why they're suddenly on first name basis, but was casually ignored or misheard. Instead they settled for a comfortable silence, passing many corridors and unused rooms while lights hung brightly above them. Again, the menacing voice returned to her head. _'Do it now. It's just the two of you. Alone. In the dead of night.' _Her hands shook violently. _'Just push her against the wall and wring your hands around her pretty little neck. DO IT. NOW!'_

"No..."

"Did you say something, Marceline?"

She stopped walking, blinking out of her trance once the voice went away, and saw that they were back at her bedroom door. A yawn roared from her mouth. Thinking was exhausting sometimes. "I didn't say anything... Bonnibel. But I should probably return to bed. I'm surprisingly tired after your "tour"." Marceline had her hand on the doorknob. She pushed her glasses up. "Of course of course. Today the Candy Kingdom is having a royal ball in the castle and as my royal adviser, you must be present and by my side. Make sure you up and dressed bright and early."

"I don't have anything to wear," she said, trying unsuccessfully to get out of event. Bonnibel hollered over her shoulder before entering her room,

"I'll have something waiting for you before you wake. Good night!"

Sigh. Nothing she could do about it now. Somehow she managed to at the least nap the rest of the night away.

* * *

"Um. This isn't _exactly_ my style."

The vampire teen looked at the pink monstrosity on her dresser where she found it that morning. Bonnibel pinned her hair in a bun in Marceline's bathroom, a bobby pin in between her teeth.

"It's not going to kill you, Marceline. Now put the floppin dress on!"

Oh. But Marceline was _certain_ that if she put it on, it would devour her in fluff and ribbons. She hissed at the grown, staring daggers until it jumped out the window in fear. A knock filled the room and peppermint butler called from behind the closer door,

"Marceline, if you don't enjoy your gown, I can arrange for something more in your _style_ as you say."

After a flurry of measuring and color schemes, Marceline wore a high and low black strapless, sweetheart collar with ruffles all around besides the torso. With black heels and wavy black hair, she sat proudly by Princess Bubblegum's side in the brightly lit ballroom. She rested her head in her hand, watching boring subjects dance and giggle in _just_ the right pitch to annoy her.

Beside her, Bonnibel displayed herself proudly as the ruler of the Candy Kingdom with an air of grace that Marceline herself couldn't even _fathom_ obtaining. Was that what was expected of her? Seeing her all high and mighty made her want to see the relaxed teen that sung and made songs in her past time. And she had the perfect plan to do just that. "Psst," she whispered, her hands cupped around her lips to emphasize the sound. "Princess! Meet me in the garden!"

Bonnibel raised a single arched eyebrow, her curiosity peeked. "What for?"

"It's a surprise." And with that said, Marceline vanished. She waited impatiently in the garden, sniffing a single red rose before sucking out the hue.

"I'm here. What do you want," Bonnibel said, announcing her appearance with arms raising by her side and dropping heavily. The vampire smiled when she walked up to the pinkette and poked her upper arm.

"Tag. You're it!" She ran in the opposite direction, diving into the tall maze while laughing childishly. Marceline wasn't sure how long they played the kiddish game; The laughter rang loudly throughout the maze. When Bonnibel came close to tagging her, she floated high into the air. Amazed, she looked up at her in awe. "Oh my glob, you can fly?"

"Yeah! You wanna join me?"

She lowered herself enough to grab Bonnibel by the hand and tug her into the air effortlessly. Flailing, she clung to her waist desperately, burying her head against her chest. The vampire's heart fluttered rapidly, looking down at the blushing teenager. A soft smile lingered onto her face. The two sailed in the air, bathing in the wind whipping through their hair, messing up the younger's perfectly styled bun. Eventually, duty called and the two returned to the dull ball room.

Marceline fondly remembered the look of wonder on her face when she retired for the night. The way her cheeks blushed and her blue eyes widened... Wait. She was doing it again. Where was her since of duty? What happened to go in, kill, and leave? _'Bonnibel is what happened,' _She thought. But she had a duty to her own kingdom. To her father.

Sigh.

She's been doing that a lot lately. A cloud of fog emerged in front of her, an image of her father appearing like a web cam call.

"Hello. I just wanted to remind you that you're on a bit of a time crunch. Steal the throne for Daddy! I know you're busy so I'll leave you to your evil devices. Bye bye now." The cloud faded and Marceline groaned at the reminder, reaching into her satchel and tucking the knife underneath her pillow. The next time she saw her, that knife _will_ be put to use.

It _had_ to be.

A violent thunder boomed from outside, stunning the vampire. She rushed in her bag to find her doll Hambo before the next roar came. Her heart jumped out of her chest at the second round. Hambo wasn't in the bag. She didn't bring Hambo! A yelp leaped out of her mouth when lighting flashed. Footsteps sounded from next door.

"Marceline? Are you okay?"

Those same glasses sat on her nose when she peeked behind the door. She was about to laugh it off like it was nothing, but when another round came she cringed and whimpered. Bonnibel smiled at the adorable teenager, offering a hand.

"Come on. You can sleep in my room for the night."

Without another word, they slipped into the satin pink sheets on different ends of the bed. The storm outside calmed down to a gentle pattering against the window.

"Hey, Bon bon?"

"Yeah?"

"How did you feel when you took the throne?"

The two faced each other now, their hair mixing together from the closeness. "Well. At first, I felt trapped. Like I got the raw end of some whack job deal. It didn't grow any greater nor lesser, but then I got a new royal adviser."

Marceline's eyes widened, scooting closer to pinkette. "Really. Tell me about this royal adviser."

"It was a girl around my age with pale grayish blue skin and dark colored eyes, long wild black hair reaching the floor. We met when she peeped on me singing and there was something in her eyes that made me like her. _A lot._ And somehow I ended up in bed with her. And now I don't feel so alone. I feel like if she's by my side I can let loose and still rule a kingdom. But the real question is how she feels about that."

The two during the talk drew closer and closer. When Marceline talked, her breath tickled the other's nose. "I have a feeling she likes you too. _A lot. _

"Oh yeah?"

"Yeah.."

"Well then why are we doing here talking when we could..."

She leaned in and felt the gentle pressure of lips on her own. They were soft, warm, and gently moving against hers, persuading her to react. She trailed a hand up her arm, rubbing the pink tinted skin, tilting her head to deepen the kiss. Her brain turned into mush when Bonnibel tugged her bottom lip, suckling and nibbling away. Marceline's hand instead ran along her waist, bringing her closer. A hand made its way into the scalp of her black locks, a sneaky tongue slipping into the kiss to explore her mouth. A moan came out of absolutely nowhere. The princess fiddled with the hem of her pajama shirt, going underneath to feel the smooth skin of her waist.

The kiss broke as they chased air back in their lungs. Before Bonnibel could speak, Marceline pecked her pretty pink neck, starting at nibbling her collarbone and then running to just behind her ear, earning a yearning call of her name.

"Marceline."

There names were the only thing heard for anyone listening in that night. Only the two knew personally about the smoothness of legs and thighs, the broken moans when pleasure spots were discovered, the clinging onto each other when things grew too intense in pace and sensations dancing lustful on their sweaty, nude bodies. Only Marceline and Bonnibel understood just how emotional the sexual experience ways, the connection that couldn't be avoided from such a deep joining.

When Bonnibel curled against the big spoon Marceline, her mind was made up. She couldn't kill her, couldn't take the life from her eyes with her own bare hands. What did she have to loss? A kingdom wanting to conquer and control others selfishly with her as the queen? Her answer was definitely made. Tomorrow, she'll contact her father and tell him the deal was off.

For now, she focused on her lover's gentle breathing and the curve of her hips underneath the cover before dozing off to a nap with the glow of the full moon bathing them in lunar light.

* * *

Thank you for reading the 2nd chapter of I Can't Kill Her. I'm having such an awesome time writing this! Sorry if the lime is kinda crappy, it's my first Yuri one. Til the next chapter, mustaches.


	3. Chapter 3

This is it. The final chapter of 'I Can't Kill Her'. Will things become happily ever after for the couple or will a tragedy ruin everything?!

**Warnings: Yuri fluff**

**Disclaimer: I do not own Adventure Time.**

* * *

Marceline squinted her sleepy eyes, her sensitive ears hearing yelling and the crashing of furniture. When she sat up and looked around, Banana Guards were raiding her room, some huddled behind an angry Princess Bubblegum. A yellow hand yanked her out of bed and handcuffed her thin wrists, she struggled against the guards hold until she heard a her voice take a darker tone.

"Marceline Abadeer, you are arrested for treason among the Candy Kingdom. You have the right to remain silent..."

Her mind went blank when Princess Bubblegum told her her rights. She heard herself saying,"What are you talking about, Bonnibel?! Treason?" A random guard spoke up, "We heard you talking to the King of the Nightosphere about assassinating the princess. We also found what would have been the murder weapon underneath the pillow." Marceline gasped. She completely forgot about the knife!

"Marceline is this true? You planned to assassinate me?"

She hung her head low in shame and mumbled, "I can't deny it, Bonnibel."

"You are to address me as Princess Bubblegum. Take her away." Marceline breath caught in her throat the utter chill in her voice, but while she was taken away she looked into her eyes and saw tears brimming at the rim and... sadness. Chills ran down her spine knowing that she caused her to feel that way.

This wasn't how things were supposed to turn out. She had it all planned in her head. Tell her father the deal was off and live alongside Bonnibel in the Candy Kingdom. It would've been perfect. Now here she was rotting in a crummy prison cell several floors underneath a girl she actually cares about. She knew she could escape at anytime, simply grow into her demonic form and wreck everything in sight. But knowing that Bonnibel would never look at her the same made her stay.

It's time to pay for what she did. Or didn't in this case. Consequences are consequences.

In the cold, damp cell she thought long and hard about what she did, arguing with the nasty voice in her head from time to time. Every now and then she was feed some candy, making her stomach kinda queasy, but she sucked the red from peppermints and strawberries whenever they came in the mix. Growing out her nails at will, she dug tally marks in the stone wall.

On the 7th day (or night, she couldn't tell time in the windowless prison), a familiar gray fog seeped from the gravel floor, manifesting to the man that got her in all of this drama in the first place. Hunson Abadeer, the infamous King of Evil, stood in front of the bars in his everyday midnight tux. Resting his arms on an invisible stool, he quirked an eyebrow at his suffering daughter.

"Why Marceline, how did you get in this predicament? Was the task too hard to do?"

She remained silent, praying in her head that he'd bugger off, that he can just leave her be. But there was always something about her father that made her react. She growled,"I didn't want to do it and I do what I want."

"Why the change of heart little Marceline? Just 9 days ago, you accepted the mission without this... attitude," he said, pointing a pointy finger at the disheveled girl. Marceline sighed, deciding to be honest with him for once.

"Father, I thought I could do it, but well I kinda maybe sorta... caughtfeelingsforthetarget." There. It was sad and done. Even if the words ran into each other when she said them. But it was a relief to tell someone about it. His eyes widened, little flames lit in them.

"YOU fell for Princess Bubblegum? How could you, Marceline? You're an Abadeer, not some candy kingdom ditz!"

Her hands tightened on the steel bars. "Don't talk about her like that," she barked, canines appearing in her snare.

"I'll talk about her however I want. What could you possibly see in that bubblegum girl?"

She answered honestly, mind fondly recalling her Bonnibel. "I see a teenager caged in responsibility that just wants to let loose like I do! Like how you caged me into being the heir of the Nightosphere. I don't want that life, Father. I just want to hang out with her here and be teenagers in love..."

He hissed out,"In love? More like in lust. Maybe a little time in here will do you well after all." And just like that, Hunson vanished, leaving her alone with her own thoughts and sighs once again. But surprisingly, she heard the door at the top of the long set of stairs open. Light footsteps traveled down until Marceline saw a hint of pink hair and smiled despite her sadness. Princess Bubblegum, prim and proper, pulled up a chair near her cell. Her hands nervously sat on her lap. The two didn't say anything; Marceline because she didn't want to say the wrong thing and PB because she didn't know how to start.

"I... I heard you talking to your father just now... Do you really love me?"

A furious blush grew on her bluish gray cheeks. But despite her embarrassment, she replied,"I don't know if I'm in love, but I know that you make me feel different. The good kind of different. The kind I want to feel a bit more with you." She'd probably regret that answer later. Not very smooth.

"Hmm."

The silence lurked in until Marceline coughed and said,"I'm sorry. For all of this. I don't blame you if you never talked to me again."

"I forgive you. I'm... sorry I didn't trust you. I shouldn't have thrown you down here, but I had to think and..."

"And," she whispered in hope.

"And I think," the princess said, pulling out a loop of keys and opening the prison cell," we should start over. No assassin, no princess. Just Marceline and Bonnibel. Can we do that?"

Marceline left the cell and smiled like the happiest vampire in the world. "We can." She pulled Bonnibel close to her by the waist, jumping in joy when she wrapped her arms around her neck and snuggled into her chest. The were still, enjoying the intimate contact and the reassuring sitting in the embrace. Marceline sighed, sniffing her sweet sticky hair and kissing her pink rosy cheeks. This was where she belonged.

* * *

"And that, little candy children, is the story of the Assassin and the Princess. The end."

The sweet kids cheered and clapped when the story ended. A green lollipop raised her hand, asking,"I don't get it. Do they get together or what?" Marceline quirked an eyebrow at the grinning princess beside her, giving her the question.

"Let's just say they lived happily ever after, okay? Now off you go!"

As the children left the story time room, the vampire walked behind them, squeezing her lover's pink waist and kissing her blushing cheek.

"Pfft. I would've told it better."

* * *

Thank you for sticking with me to the end of this Bubbline fluffy love story. I'd love love love to hear how I did on the story so leave a review! See you next fanfic.


End file.
